1. Field of the Invention
The present invention relates to an optical disc recording and playback apparatus that is configured so that a signal is recorded to disc by a laser emitted from an optical pickup and the signal recorded on the disc is played back by the laser.
2. Description of the Related Art
Disc players for reading signals that have been recorded on discs using optical pickups have become pervasive. Recently, in addition to the playback function, disc recording and playback apparatuses configured so as to enable signals to be recorded onto discs by a laser emitted from an optical pickup have become commercialized.
In an optical disc recording and playback apparatus, it is necessary to accurately aim the laser beam emitted from the optical pickup to a signal track on the disc surface for performing focus control and tracking control operations. The related focus control operation is performed by supplying driving current to a focusing coil for displacing an objective lens toward the disc surface, and the tracking control operation is performed by supplying driving current to a tracking coil for displacing the objective lens in a radial direction on the disc.
Recently, the trend has been to increase the signal density so as to record more signals onto a disc. To increase the density, it is necessary to optimally aim the laser beam onto the disc. To perform this operation, an operation for correcting the relative angle of deviation between the disc and the objective lens, namely, an optical pickup configured so as to allow a tilt adjustment, has been developed. (For example, refer to Japan Patent Laid-Open Publication No. 2002-197698.) Additionally, a technique for detecting the tilt of the pickup with respect to the disc and for adjusting the tilt has been developed. (For example, refer to Japan Patent Laid-Open Publication No. 2002-208155.)